"The Seafarer" is an Anglo-Saxon elegiac poem which laments the narrator's loss of everything. In the opening, the narrator states that story is his (assumed male based upon the typical gender of the seafarer during the period). He provides the reader with an honest and emotional look at his life, both past and present.
In the opening, the seafarer speaks about his heart being frozen (figuratively) by icy bands and frozen chains (the same as the ones which hold his feet). The only thing which is able to force his heart to beat is to be upon the sea.
And how my heart
Would begin to beat, knowing once more
The salt waves tossing and the towering sea!
The seafarer only has the sea left. He has no one left to comfort him, all his kin and friends are gone. Only the sea can move the heart of the broken and frozen man. Faced with having nothing left, the seafarer is forced out upon the sea again. He has known the sea his entire life, and it is all he has left.